R控制檯提供輸出，無論錯誤如何，但Shiny應用程序不會因錯誤而失敗。我如何繞過Shiny應用程序中的錯誤？

Question

當我在R控制檯運行下面的代碼時，得到下面的錯誤在管線10：

「錯誤在lda.default（X，分組，...）： 變量5 6似乎是恆定組內「

但是，其餘的代碼仍然處理和數據繪製。但是，當我將這些代碼集成到我的閃亮應用程序中時，情節面板將顯示錯誤消息，而不是其他任何東西

有沒有辦法解決這個問題？

輸入：

require(MASS) 
require(ggplot2) 
require(scales) 
require(gridExtra) 

x = 'Species' 
ex = iris[, x] 

lda <- lda(ex ~ ., iris) 

prop.lda = lda$svd^2/sum(lda$svd^2) 

plda <- predict(object = lda, newdata = iris) 

dataset = data.frame(colAndShape = iris[,"Species"], lda = plda$x) 

p1 <- ggplot(dataset) + geom_point(aes(lda.LD1, lda.LD2, colour = colAndShape, shape = colAndShape), size = 2.5) + 
    labs(x = paste("LD1 (", percent(prop.lda[1]), ")", sep=""), 
    y = paste("LD2 (", percent(prop.lda[2]), ")", sep="")) 

grid.arrange(p1) 

控制檯輸出：

> require(MASS) 
> require(ggplot2) 
> require(scales) 
> require(gridExtra) 
> 
> x = 'Species' 
> 
> ex = iris[, x] 
> 
> lda <- lda(ex ~ ., iris) 
Error in lda.default(x, grouping, ...) : 
    variables 5 6 appear to be constant within groups 
> 
> prop.lda = lda$svd^2/sum(lda$svd^2) 
> 
> plda <- predict(object = lda, 
+     newdata = iris) 
> 
> dataset = data.frame(colAndShape = iris[,"Species"], lda = plda$x) 
> 
> p1 <- ggplot(dataset) + geom_point(aes(lda.LD1, lda.LD2, colour = colAndShape, shape = colAndShape), size = 2.5) + 
+ labs(x = paste("LD1 (", percent(prop.lda[1]), ")", sep=""), 
+  y = paste("LD2 (", percent(prop.lda[2]), ")", sep="")) 
> 
> grid.arrange(p1) 

Answer 1

您的通話lda一個錯誤。公式中不提供變量名稱，而是提供因子向量。您應該使用paste或sprintf和as.formula從變量構造公式。

x = 'Species' 
lda <- lda(as.formula(paste(x, ".", sep = "~")), iris) 

prop.lda = lda$svd^2/sum(lda$svd^2) 

plda <- predict(object = lda, newdata = iris) 

dataset = data.frame(colAndShape = iris[,"Species"], lda = plda$x) 

p1 <- ggplot(dataset) + geom_point(aes(lda.LD1, lda.LD2, colour = colAndShape, shape = colAndShape), size = 2.5) + 
    labs(x = paste("LD1 (", percent(prop.lda[1]), ")", sep=""), 
    y = paste("LD2 (", percent(prop.lda[2]), ")", sep="")) 

p1 #grid.arrange(p1) isn't needed in this example.